1. Field
The following description relates to an apparatus for generating plasma; more particularly, to an apparatus for generating plasma, including an upper electrode and an inductive coil.
2. Description of the Related Art
Generally, an apparatus for generating plasma is an apparatus for dissociating a reaction gas using an electromagnetic field, thereby generating free electrons, positive ions, neutral atoms, neutral molecules, etc.
FIG. 1 is a schematic cross section of an apparatus for generating plasma according to the conventional art. As one example of the conventional art, FIG. 1 illustrates an Inductively Coupled Plasma (ICP) type plasma generating apparatus 10.
The plasma generating apparatus 10 includes a vacuum chamber 11, a dielectric part 12, an inductive coil 13, a cover 14, a Radio Frequency (RF) power supply part 15, and an ElectroStatic Chuck (ESC) (or a susceptor) 16.
As illustrated in FIG. 1, the electrostatic chuck 16 is installed inside the vacuum chamber 11, and a target substrate 3 is mounted on the electrostatic chuck 16. An electrostatic chuck elevator 17 is installed below the electrostatic chuck 16. The dielectric part 12, the inductive coil 13, and the cover 14 are installed on the vacuum chamber 11, and are sealed by a case 18. A gas inlet 14a is formed at one side of the cover 14. The RF power supply part 15 includes an RF source 15a and a source matcher 15b. 
When a bias RF power is applied to the electrostatic chuck 16 and an RF power is supplied to the inductive coil 6, a magnetic field 5 is formed around the inductive coil 13. In result, an electric field is induced within the vacuum chamber 11, and plasma (P) by inductive coupling is generated within the vacuum chamber 11.
The ICP type plasma generating apparatus 10 has an advantage of being capable of generating plasma of a higher density than a Capacitively Coupled Plasma (CCP) type plasma generating apparatus (not shown). Accordingly, intensive research on the ICP type plasma generating apparatus has been made.
However, because the plasma generating apparatus 10 uses only the inductive coil 13 as a means for forming an electric field within the vacuum chamber 11, the plasma generating apparatus 10 tends to non-uniformly form the electric field within the vacuum chamber 11.
As illustrated in FIG. 1, because the magnetic field 5 is intensively distributed only around the inductive coil 13, the electric field induced by the magnetic field 5 also concentrates at a lower part of the dielectric part 12. In result, a plasma density 7 is lower in a center region of the target substrate 3 than in an edge region of the target substrate 3. This phenomenon happens more seriously in a plasma generating apparatus for a large-size target substrate.
Also, because the plasma generating apparatus 10 cannot diversely vary the distribution of the electric field, it is difficult to variously control the distribution of plasma within the vacuum chamber 11.